Method of stroboscopically observing rotating bodies and apparatus therefor



May 30, 1933.

E. HIME METHOD OF STROBOSCOPICALLY OBSERVING ROTATING BODIES AND APPARATUS THEREFOR Filed May 11, 1929 5 Sheets-Sheet l May 30, 1933. E. HIME ,3

METHOD OF STROBOSCOPICALLY OBSERVING ROTATING BODIES AND APPARATUS THEREFOR Fil d May 11, 1929 5 Sheets-Shes}, 5

INVENTOR I wk...

Hi5 ATTORNEYS May 30, 1933. E, HIME 1,911,363

METHOD OF STROBOSCOPICALLY OBSERVING ROTATING BODIES AND APPARATUS THEREFOR Filed May 11, 1929 5 Sheets-Sheet 4 I 7/ all/111A ELEVATION INVENTOR 5L4.

. BY EW.;. QMM'M HIS ATTORNEYS May 30, 1933. E. HIME 1,911,363

METHOD OF STROBOSCOPICALLY OBSERVING ROTATING BODIES AND APPARATUS THEREFOR Filed May 11, 1929 5 Sheets-Sheet 5 INVENTOR W 511;, BY GiMw -w HIS ATTORNEYS Fatented May 30, 1933 UNITE STATES PATENT 'oFF- c'E:

'EUGENIO HIME, on 310 DE JANEIRO, BRAZIL;

METHOD or sTRoBosooPIoALLY onsnnvmo nor-Arrive ooms AND APPARATUS,

HEREFOR Application niearra 'irieae, Serial No. 362,180, and in. Brazil April 1, 1929.

The present invention relates to a method of rendering visible bodies endowed with rotary motion through the immobilization of their image; and its object is to provide 6 means which make it possible to observe through the apparatus directly" or through projection, the rotating body as if it were stationary, thus rendering it possible to get a clear imageof the body and to ascertain 10 its appearance under the action of said motion.

Broadly, the present method consists of the provision of an optical medium in which a cylindrical or conical beam of light passing through it is subjected to a certain number of reflections, which force it to follow a pre determined path. The reflections may be three or five in number. At the same time, to the optical mediumis imparted a variable,

controlled and adjustable rotary motion about a straight line (axis of rotation), par-' allel to or coinciding with the direction of the incident and emergent beams, the angular velocity or number of revolutions being measured by means of a velocimeter or counter of revolutions coupled to the apparatus.

The optical medium, provided in accordance with the invention, may be secured in practice, through combinations of prisms, mirrors, lenses and the like, as desired; and the apparatus thus carried out may serve for direct observation in the apparatus itself or for projection on a translucent or opaque screen.

The apparatus may be enclosed or secured to a metallic or other case, mounted so as to be capable of rotating at any desired speed.

Obviously, the apparatus may take the 4 most varied forms, through the combination of known optical and mechanical devices, according to the requirements of every case.

In this way and for a better understanding of the invention, the following description is made with reference to the appended drawings, in which is shown schematically the path of the beam of light, according to the two above mentioned ways and in which: Figure 1 is a diagram of the path when the beam of light is subjected to three'reflecand the reflected beam R R tions; and Fig. ,2, a similar diagram, when the beam of light is subjected to five reflections. 1 Fig. 3 is a vertical elevation, partly in ,7 section, of one form of means for carrying out the principle illustrated in Fig. 2;

Fig. 4 is a cross-section online 44 of Fig. 8, sighting in the direction of the arrows;

'Fig. 5 isa vertical elevation,*partly in section, of another embodiment ofthe principle shown in Fig. 2, and

i Fig. 6 is a cross-section on line 66 of Fig. 5 sighting in the direction of the arrows.

Fig. 7 is a vertical elevation, partly in sec tion, of an embodiment of the principle of Fig. 1; F ig'. 8 is a sectional "plan thereof; Fig 9 is a view similar to Fig. 7, the prism here having a face angled so as to direct the light towards the axis of rotation, and Figs. 10, 11 and 12are similar-respectiveviews of a further embodiment of the principle'of Fig. 1. j I

In Fig. 1, the beam of light from C is reflected by a surface. R to another surface R which in turn reflects it to a third surface R by which it is reflected, finally, toward the observer or projected on a screen. The re fleeting surface R is arranged so that it reflects the beam of light in a direction more or less normal to the plan formed by the two former-paths, that is, the incident beam CR Now, if any desired rotary motion be 'imparted to the assembly of reflecting surfaces R R andR about CR as anaxisythe ob serverplaced at O and looking in the direction' 0R will see the image of'any point P of an object S describe a circle about, C, with an angular velocity exactly equal to twice the angularvelocity imparted to the optical device.

For the convenience of the observer who, in the case of Fig. 1, would have to displace his eye so as to describe a circle having a radius R 0, the apparatus shown in Fig. 2, may be employed, in which the beam reflected by R is directed towards a surface R which reflects-it toward another surface R G5 suitable distance.

which directs it so that it will emerge from the apparatus as an extension of the initial beam CR A working embodiment of the principle shown in Fig. 2 is illustrated in Figs. 3 and 4 and comprises a casing A in the form of a short hollow cylinder having central shafts B and C integral therewith. The casing is mounted suitably in bearingsD and E, shown diagrammatically, and is rotated therein about its shorter axis by means of power suitably applied to a pulley F fixed to the lower end of one of the shafts. This pulley may, of course, be suitably connected to the rotating object the condition of which is to be observed, instead of being connected to a separate source of power. Within the casing there is a prism FSIBCAJ H, shown in elevation in Fig.3 and in bottom plan in Fig. 4:, this prism being attached to the casing in any suitable mannerwith the point B on the axis of rotation of the casing. This prism is formed from a single block with dihedral angles and faces such that the light entering the hollow shaft B from the rotating object is first totally reflected upwardly from face SFHB at the point R as seen in Fig. l, from its entering horizontal plane and then passes through the plane R 11 being reflected from face AIJ H downwardly in the same vertical plane to the point B on the surface BAHC. From the point R the light ray is reflected rearwardly in a horizontal plane, parallel to its entrant path but offset considerably to the left thereof.

. Attached to the casing in any suitable manner andlying back of the first prism, is another prism KNML, shown in plan in Fig. 8 and in elevation in Fig. 4. Instead of being a three-total reflection prism, this prism is a two-total reflection prism, and reflects the ray received from R at the point R in the vertical surface having the edge MN in a right angle direction to the point B on the surface KL. M From this point the light ray is reflected as a continuation of its original path, andenters the eye of the observer.

Thus, the device being rotated at half the speed of the object under observation and in the oppositedirection thereto, the object will appear to the observer to be stationary, so that he can record the exact condition of the body due to the rotation thereof.

In Figs. 5 and 6 there is illustrated a modification of the device shown in Figs. 3 and 4, differing therefrom chiefly in that for the single three-reflection prism at the entrance to the device, there is substituted two singlereflection prisms abcrl and efhg, these-prisms being identical with each other. These prisms are suitably attached to the casing with the center of prism abcd on the axis of rotation of the device, and with the center of the other prism offset to the left therefrom a The horizontal entering light ray is reflected first upwardly in a vertical plane at point B on surface dba as shown in Fig. 6, and leaves the prism. A mirror jilic is mounted suitably adjacent the prisms in a vertical plane and behind them in Fig. 6, and the light reflected from prism abcd strikes this mirror at point R From the point R the ray is reflected downwardly to the point R on the surface glue in the prism efhg, whence it is reflected rearwardly parallel to its entrant path, but offset considerably therefrom. Two mirrors ma and p0 are mounted vertically in the casing, in clines towards the other side of the casing and the left mirror mareflects the light at point B; to point B on the ,othermirror, which in turn reflects the light to the eye of the observer.

The prism'KMNL of Figs. 3 and may be dispensed with if desired, the apparatus then embodying the principle of Fig. 1, as.

shown in Figs."7.9 inclusive, the light then ing reflected three times and the emergent ray being observed from a point off centre from the rotating casing. By such means, a much cheaper apparatus can be used to accomplish practically the same result as before, but this form none-the-less' embodies the principle of deflecting at least one of the rays in a plane perpendicular to that of the other reflections.

The mirrors MN and OP of Figs. 5 and 6 may also be dispensed with to form the embodiment shown in Figs. 10 to 12 inclusive, retaining only the single mirror jiclh, this embodiment then carrying out the principle of Fig. 1 in substantially the same manner.

In all the embodiments illustrated, it is contemplated, however, that the entering ray be first reflected in a plane normal to the plane of the other paths of the light, whereby there is produced an apparatus in which are eliminated much of the paraphernalia hitherto required, and enabling the device to be constructed so small and compact as to be adapted to be employed in very close quarters, yet none the less making possible a clearer and more satisfactory observation of the rotatingbody.

The apparatus ust described and shown its schematically in the drawings possesses the following properties: i

(1). If any object, stationary with reference to the observer, be viewed through the apparatus and the latter is made to revolve about its axis of rotation through a certain angle A, the image of the object looked at will rotate through an angle 2A from its original position, with the optical axis of the apparatus as a center.

(2). If any object or device endowed with rotary motion be observed throu h the apparatus and the latter is given a rotary motion, the angular velocity of the observed image will vary, increasing ordiminishing with reference to the velocity of the object, according as the apparatus is rotated in an opposite or in the same direction asthe object.

(3). When the rotation of the apparatus is in the direction which causes a diminution of the angular velocity of the observed image, the latter will be seen absolutely stationary with reference to the observer, if the angular velocity of the apparatus is equal to one half the angular velocity of the object.

With the above properties, the apparatus may serve to give the impression of being stationary a body endowed with a rotary motion; and this whether it is used by itself or adapted to any other optical device.

It is apparent that the apparatus may thus have numberless practical applications. IVith the apparatus, one can observe, directly or through projection, the stationary image of a disk which is being played in a talking machine, thus being able to read the title on the disk, without stopping the machine. In this case, the apparatus may be driven manually, by means of clockwork or through the mechanism driving the disk, to maintain constant the ratio of 1 to 2 between the angular velocities of the apparatus and of the disk.

Another application, of the numberless ones the apparatus may have, is to measure the velocity of rotation of the helixes of airplanes, of flying wheels, of locomotive driving wheels and those of any other vehicles in motion.

In industry, the apparatus may serve to render visible or to photograph what takes place within centrifugals, mixers and similar machines; or to show the behavior of balls in ball bearings; or to measure the slipping of belts or pulleys, by coupling the apparatus to the shaft.v

In addition, the apparatus may be useful in cinematographic or photographic or projection tricks or even as an interesting toy.

The apparatus may also be used to increase the precision of a variety of measuring devices, operating as an angle multiplier.

Two or more apparatuses may be mounted in series, with their axes of rotation alined, to multiply the effect. With one apparatus, as hereinbefore mentioned, the ratio of the angular velocities of the apparatus and the object, to make the image of the latter stationary, is 1 to 2. With two apparatuses, ar-

ranged in series, the second rotating in a direction opposite to that of the first and with the same angular velocity, the ratio of the angular velocities of the apparatuses, and the object, so that the image remains stationary, is 1 to 4: or 1 to 2 Wth three apparatuses, under the same conditions, the third one rotating in opposite direction to that of the second, the ratio of the angular velocities, to

" make the image stationary, will be 1 to 8, or

to"-2, the" legrponent of 2-expressing: the

number apparatus'coupled together. I I

' jInia ggeneral-way, mounted as specified, the apparatus of odd numbers rotatingin one direction and those direction, the ratioof the angular velocities ofthe apparatus and the rotating object, to make the image of therlatter stationary, is

K, Having thus fully described my invention, what Icla'im" as new and desire to secure by Letters Patent is: I '1.=The]method of stroboscopicall'y observ ing rotating bodies comprising immobili'z!v ing their image by reflecting a light there-- fromfsub'jec'ting the light rays from said body to at least 'three non-coplaner reflections and rotating these reflections ata speed less than that of the rotating body and in the same-direction thereto. I ,-J2;?A"device of the classdescribed, com prising a casing having hollow central'shafts attached thereto, bearings for the shafts,

means. for'rotatingthe casing in thebearrotating the casing in-the bearings, a c'o1nbi-.

nation of three total-reflecting surfaces for of-even numbers "rotating in the opposite the .lightxrays cut in'a singleblock located 7 in thecasing, and means in the casing for reflecting this three-reflected light rays out of the casing as a continuation of itsentrant path. I

4. A device of 1 the classldescribe'd, coma prisinga casinghaving hollow central shafts attached thereto, and adapted to receive light rays, bearings for the shafts, means for-rotating the casing in the bearings, a combination of three total-reflecting surfaces cut in a single block, located in thecasing and; a combinationof two total-reflecting surfaces for thelight rays cut in a single block, said block being arranged rea-rwardly o f said first'block in such a way as to reflect the lightrreceived from said first block. out of the casing as a continuation of the said bln a device of the class described,-a triangular prism mounted with its optical axis on the axis of rotation of the device, said triangular prism reflecting received light in a vertical direction, a mirror mounted on said prismthereabove, and reflecting said vertical ray downwardly, an identical prism mounted in parallel with said first prism and underneath said mirror, said prism reflecting'light received from said mirror" in a'horizontal direction, another mirror mounted verticallyv in said; casing with its center on the optical axis of said second prism, said mirror reflecting light I 5 received from said second prism at right angles thereto, and a third mirror mounted vertically in said casing with its centerv on the axis of rotation of said device, said third mirror reflecting light received from s'aid second mirror as a continuation of the-Hentrant ray. v 7

' '6. In combination, a shaft, a p'luralityfof the devices of claim 8 mounted thereon in a straight line along the'axis of'theapparatu's for rotation in different directions, and

means for rotating adjacent ones of said devices in opposite directions thereby immobilizing the light-rotations.

7. The improvement in the method ;of

' stroboscopically observing rotating bodies,

comprising causing a beam of light to emanate fromthe rotating body, and subjecting said beam to three reflections, directing the path of said beam on the second reflection substantially normal to the path of the beam undergoing the first reflection, and directing the path of the beam on the third reflection substantially normal to the plane formed by the incidence-beam of the second reflection and the reflection beam of'the'first reflection, at the same timerotating the beam undergoing reflection in the same direction as that of the rotaitng body and at a lesser angular velocity. a Y 3,5 8. The improvement in the method of str'oboscopically observing rotating bodies by immobilizing their images, comprising causing .a beam of light to emanate from the rotating body, and subjecting said beam to five total reflections, directing the path of said beam on the second reflection substantially normal to the path of the beam undergolng the first reflection, directing the path of the beam on the third reflection substantially normal to the plane formed by the incidence-beam of the second reflec tion and the reflection beam of the first reflection, directing the said beam on the fourth reflection towards the geometric prolongation of the initially-incident part of the beams, the said beam portions being thereby caused to intersect, and subjecting the beam'thereat to a fifth reflection whereby the emergent beam lies in the prolonga- T tion of the initial beam, at the same time rotating the beam undergoing these reflections in a direction opposite to that of the rotating body and at a lesser angular velocity. 1 i

"" 0 In testlmony whereof I afiix my signature;

EUGENIO HIME. 

